1. Field of the invention
The present invention relates to a transition pipe for location in a jet pipe assembly of a turbojet engine between an afterburner pipe and a jet nozzle.
2. Summary of the prior art
In a turbojet engine the afterburner pipe in which the gases intended for discharge circulate usually has a generally circular cross-sectional shape. Research aimed at improving performance, simplification, and various other objectives, such as the reduction of overall size or kinematic optimization, has led, in some cases, to the use of jet nozzles of the type known as "bi-dimensional", the fixed structure of which has a square or rectangular section. French Pat. No. 2608680, for example, discloses an adjustable bi-dimensional jet nozzle of this type.
French Pat. No. 2326585 also relates to a bi-dimensional jet nozzle assembly. The transition pipe envisaged is not, however, satisfactory for certain applications and, in particular, the construction proposed poses a number of difficulties as regards the use of composite materials, which exhibit advantageous characteristics at the high temperatures encountered in use. In particular, with the known constructions the transition pipe is subjected to bending moments as a result of the mechanical stresses which develop during use, the thermal expansions exerted in differential manner on various elements, and deformations.
The object of the invention is to provide a transition pipe construction which reduces the mechanical stresses to simple tensile or compressive stresses, reduces mechanical stresses of thermal origin, and enables achievement of an optimum distribution of thicknesses making it possible to obtain a reduction in mass and permitting a different selection of materials, particularly of composite type, and their use under the best conditions for their performance in service depending on the type of mechanical stress, especially tensile or compression according to the particular case.